MAF Transfer and Injector Slopes

Discussion in '1994 - 1995 Specific Tech' started by Joes95GT, Jan 11, 2006.

  1. OK, here's the deal...

    I just started screwing around with my Tweecer again, trying to dial in the MAF curve and Injector slopes. Keep in mind that I'm only altering the MAF curve under ~2.6 volts because my trans is going to explode any day now. It needs to last me about another 1-2 months and it's getting rebuilt, so I'm not going to beat on it hard.

    I hijacked the Pro-M 75mm MAF Transfer for my 76mm C&L and altered it slightly to get my KAMRF's close. Keep in mind this is all towards the lower end of the MAF curve, with no attention paid to the upper half.

    With that said, I got my KAMRF's close (1.06-1.10), so I started screwing with the EEC Analyzer's Injector Slope/Injector info program where you just upload the datalog and hit the "calculate" button. After doing two separate datalogs (disconnecting the battery for ~30 minutes both times), EEC Analyzer has give me a high slope of 23, a low slope of 27 and a BP of 3.045 (where ever that came from? :shrug:), which is a far cry from the 32 and 24 that I had it set at originally.

    The KAMRF's are almost EXACTLY all 1's across the board, but my Injector Pulsewidth at idle is hanging around my 3.045ms, which is my set breakpoint. This seems quite extreme...

    Here are my questions:
    1) Is that P/W normal for idle (856 RPM)?
    2) Can I lower it just to adjusting my BP?
    3) What's up with my injector slopes being so far off from the original settings? Should I go back and adjust the MAF Transfer more?

    Thanks for all yall's help!! :D


  2. Have you noticed some of the guys on the Tweecer site run C&L mafs?

    First thing I would do is see if you can find some generic C&L curves there. Clint has a good bit of C&L info on his site as well. You may be able to find some curves on the Yahoo site in the files section.

    You will be so much more ahead in the game if your curve is close to where it needs to be when starting with the tuning process. Find some more curves and see if they all are about the same as you now got.

    As for getting started on dialing your inj's...................

    First off ...... don't forget to load in offsets for the 24's

    You can speed up a pcm reset if you step on the brake, hold down the horn, turn on the head lights, etc for about 5 seconds after you disco the neg batt cable. That little trick drains the charge from everything.

    Your K values are telling you adaptive is adding 6 to 10% fuel.

    This can be seen at idle by your > 3.00 pulse width. Most peeps see 2.00 to 2.50 pw's at idle.

    NO TURNIN BACK NOW ........................

    You are right in the thick of it with .........................

    pulse widths ... break points ... lambses ... isc duty cycles :rlaugh:

    Gotta Love It :D

  3. I am guessing your running a j4j1 file with 24#inj.?

    I have a sim. setup...

    I swaped back to my stock MAF for now and plan on getting a LMAF and 70mm t-body this year sometime...have my eye on a lc1 so dont know what I am going with first.....

    With my stock MAF curve it was REAL close as it should K's were at like .9989-.9998. the inj. gave a bit of a hassle though.

    My findings were that with the j4j1 breakpoint and 24#inj. it ran like crap with what EA spit out...nothing but the 24/24 would work.

    at the track I have been sorting out some mech. issues and tried diff. tunes as well. ALL the j4j1 breakpoint runs were 14.6-14.5 at 98 with 30-31* total timing(horrible for the mods/engine setup I haveBTW). I got frustrated (imagine that) and just made a quick bare bones tune using the t4mo breakpoint and diff. slopes...ran a 14.1 @100 mph the next run with 26* total timing.

    I went home and dataloged a bit useing a j4j1 base, t4m0 breakpoint, diff. inj. slopes (24 and 24 x 1.2 or whatever it is)...I have the motor apart but the drive with just that base tune was fine and I think that will be the ticket for me. I said I have some mech. issues that I have been sorting PR that I have found to be about 1/8-1/4in too LONG just by the eyeball, meas. them this weekend to get exact...think I was floating the valves:rlaugh:

    Anyway food for thought.
  4. the idle pw will depend on the injector size.

    24# injectors will have a higher pw at idle than will 42#ers. with the 42#ers, my pw is about 1.5 at 1100 rpm and about 30kg/hr air coming in.

    there are 2 variables here: the maf transfer and the slopes/breakpoint. if you don't know either, then it is anyone's guess. that is why people usually start with a known value (usually the maf transfer) and dial in the injectors first, after i getting the injectors dialed in, then tweak the maf for minor adjustments.

    for the breakpoint, that is 3.045e-5, right? if so, that is not unusual either.

    don't adjust the bp, it will affect the kams. the bp and the slopes work together to get the fuel flow correct. i can explain how it works later if you want.

    fwiw, 23 and 27 is not too far off for 24# injectors. the j4j1 cal sets both slopes to 24, which people think because the designers didn't have time to do it right, so they made it safe by messing with the fuel and spark tables.

    i wrote a program to calc slopes and bp and analyze the maf transfer too, i'd like to run it against your log if you want to send it to me. [email protected]
  5. you can also just put an A9L cal in one of the tweecer slots and switch to it and back when you want clear the KAMs.

    (I'm TripleBlackVert over there ...)
  6. Greg brings up a very good point here Joe :nice:

    Are you using the GT or Cobra file for your combo :shrug:

    The t4m0 and j4j1 deal with inj values from very different points.

    The offsets for the t4m0 are much greater and that can make a good bit of difference. Slopes for the j4j1 are the same where t4m0 slopes are configured around IIRC, a bit more than [email protected] times the high.

    I never had much luck with the t4m0 after I went with my h/c/i stuff.

    Like me, you may be better off with the j4j1 file if you are still using the original t4m0 :shrug:

  7. I didnt make this that clear in my post...I am using a j4j1 as a base just using the t4m0 breakpoint/slope diff. thing on that j4j1.

    after re-reading it I didnt realy state it clearly that I too have found the j4j1 to be a great starting point...if I did the same things to the t4m0 it would just act funky with normal driving...nothing realy bad just not as "smooth" as the j4j1 I would run.